include/net/nexthop.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * Generic nexthop implementation
   4  *
   5  * Copyright (c) 2017-19 Cumulus Networks
   6  * Copyright (c) 2017-19 David Ahern <dsa@cumulusnetworks.com>
   7  */
   8
   9 #ifndef __LINUX_NEXTHOP_H
  10 #define __LINUX_NEXTHOP_H
  11
  12 #include <linux/netdevice.h>
  13 #include <linux/notifier.h>
  14 #include <linux/route.h>
  15 #include <linux/types.h>
  16 #include <net/ip_fib.h>
  17 #include <net/ip6_fib.h>
  18 #include <net/netlink.h>
  19
  20 #define NEXTHOP_VALID_USER_FLAGS RTNH_F_ONLINK
  21
  22 struct nexthop;
  23
  24 struct nh_config {
  25         u32             nh_id;
  26
  27         u8              nh_family;
  28         u8              nh_protocol;
  29         u8              nh_blackhole;
  30         u8              nh_fdb;
  31         u32             nh_flags;
  32
  33         int             nh_ifindex;
  34         struct net_device *dev;
  35
  36         union {
  37                 __be32          ipv4;
  38                 struct in6_addr ipv6;
  39         } gw;
  40
  41         struct nlattr   *nh_grp;
  42         u16             nh_grp_type;
  43
  44         struct nlattr   *nh_encap;
  45         u16             nh_encap_type;
  46
  47         u32             nlflags;
  48         struct nl_info  nlinfo;
  49 };
  50
  51 struct nh_info {
  52         struct hlist_node       dev_hash;    /* entry on netns devhash */
  53         struct nexthop          *nh_parent;
  54
  55         u8                      family;
  56         bool                    reject_nh;
  57         bool                    fdb_nh;
  58
  59         union {
  60                 struct fib_nh_common    fib_nhc;
  61                 struct fib_nh           fib_nh;
  62                 struct fib6_nh          fib6_nh;
  63         };
  64 };
  65
  66 struct nh_grp_entry {
  67         struct nexthop  *nh;
  68         u8              weight;
  69
  70         union {
  71                 struct {
  72                         atomic_t        upper_bound;
  73                 } mpath;
  74         };
  75
  76         struct list_head nh_list;
  77         struct nexthop  *nh_parent;  /* nexthop of group with this entry */
  78 };
  79
  80 struct nh_group {
  81         struct nh_group         *spare; /* spare group for removals */
  82         u16                     num_nh;
  83         bool                    mpath;
  84         bool                    fdb_nh;
  85         bool                    has_v4;
  86         struct nh_grp_entry     nh_entries[];
  87 };
  88
  89 struct nexthop {
  90         struct rb_node          rb_node;    /* entry on netns rbtree */
  91         struct list_head        fi_list;    /* v4 entries using nh */
  92         struct list_head        f6i_list;   /* v6 entries using nh */
  93         struct list_head        fdb_list;   /* fdb entries using this nh */
  94         struct list_head        grp_list;   /* nh group entries using this nh */
  95         struct net              *net;
  96
  97         u32                     id;
  98
  99         u8                      protocol;   /* app managing this nh */
 100         u8                      nh_flags;
 101         bool                    is_group;
 102
 103         refcount_t              refcnt;
 104         struct rcu_head         rcu;
 105
 106         union {
 107                 struct nh_info  __rcu *nh_info;
 108                 struct nh_group __rcu *nh_grp;
 109         };
 110 };
 111
 112 enum nexthop_event_type {
 113         NEXTHOP_EVENT_DEL,
 114         NEXTHOP_EVENT_REPLACE,
 115 };
 116
 117 enum nh_notifier_info_type {
 118         NH_NOTIFIER_INFO_TYPE_SINGLE,
 119         NH_NOTIFIER_INFO_TYPE_GRP,
 120 };
 121
 122 struct nh_notifier_single_info {
 123         struct net_device *dev;
 124         u8 gw_family;
 125         union {
 126                 __be32 ipv4;
 127                 struct in6_addr ipv6;
 128         };
 129         u8 is_reject:1,
 130            is_fdb:1,
 131            has_encap:1;
 132 };
 133
 134 struct nh_notifier_grp_entry_info {
 135         u8 weight;
 136         u32 id;
 137         struct nh_notifier_single_info nh;
 138 };
 139
 140 struct nh_notifier_grp_info {
 141         u16 num_nh;
 142         bool is_fdb;
 143         struct nh_notifier_grp_entry_info nh_entries[];
 144 };
 145
 146 struct nh_notifier_info {
 147         struct net *net;
 148         struct netlink_ext_ack *extack;
 149         u32 id;
 150         enum nh_notifier_info_type type;
 151         union {
 152                 struct nh_notifier_single_info *nh;
 153                 struct nh_notifier_grp_info *nh_grp;
 154         };
 155 };
 156
 157 int register_nexthop_notifier(struct net *net, struct notifier_block *nb,
 158                               struct netlink_ext_ack *extack);
 159 int unregister_nexthop_notifier(struct net *net, struct notifier_block *nb);
 160 void nexthop_set_hw_flags(struct net *net, u32 id, bool offload, bool trap);
 161
 162 /* caller is holding rcu or rtnl; no reference taken to nexthop */
 163 struct nexthop *nexthop_find_by_id(struct net *net, u32 id);
 164 void nexthop_free_rcu(struct rcu_head *head);
 165
 166 static inline bool nexthop_get(struct nexthop *nh)
 167 {
 168         return refcount_inc_not_zero(&nh->refcnt);
 169 }
 170
 171 static inline void nexthop_put(struct nexthop *nh)
 172 {
 173         if (refcount_dec_and_test(&nh->refcnt))
 174                 call_rcu(&nh->rcu, nexthop_free_rcu);
 175 }
 176
 177 static inline bool nexthop_cmp(const struct nexthop *nh1,
 178                                const struct nexthop *nh2)
 179 {
 180         return nh1 == nh2;
 181 }
 182
 183 static inline bool nexthop_is_fdb(const struct nexthop *nh)
 184 {
 185         if (nh->is_group) {
 186                 const struct nh_group *nh_grp;
 187
 188                 nh_grp = rcu_dereference_rtnl(nh->nh_grp);
 189                 return nh_grp->fdb_nh;
 190         } else {
 191                 const struct nh_info *nhi;
 192
 193                 nhi = rcu_dereference_rtnl(nh->nh_info);
 194                 return nhi->fdb_nh;
 195         }
 196 }
 197
 198 static inline bool nexthop_has_v4(const struct nexthop *nh)
 199 {
 200         if (nh->is_group) {
 201                 struct nh_group *nh_grp;
 202
 203                 nh_grp = rcu_dereference_rtnl(nh->nh_grp);
 204                 return nh_grp->has_v4;
 205         }
 206         return false;
 207 }
 208
 209 static inline bool nexthop_is_multipath(const struct nexthop *nh)
 210 {
 211         if (nh->is_group) {
 212                 struct nh_group *nh_grp;
 213
 214                 nh_grp = rcu_dereference_rtnl(nh->nh_grp);
 215                 return nh_grp->mpath;
 216         }
 217         return false;
 218 }
 219
 220 struct nexthop *nexthop_select_path(struct nexthop *nh, int hash);
 221
 222 static inline unsigned int nexthop_num_path(const struct nexthop *nh)
 223 {
 224         unsigned int rc = 1;
 225
 226         if (nh->is_group) {
 227                 struct nh_group *nh_grp;
 228
 229                 nh_grp = rcu_dereference_rtnl(nh->nh_grp);
 230                 if (nh_grp->mpath)
 231                         rc = nh_grp->num_nh;
 232         }
 233
 234         return rc;
 235 }
 236
 237 static inline
 238 struct nexthop *nexthop_mpath_select(const struct nh_group *nhg, int nhsel)
 239 {
 240         /* for_nexthops macros in fib_semantics.c grabs a pointer to
 241          * the nexthop before checking nhsel
 242          */
 243         if (nhsel >= nhg->num_nh)
 244                 return NULL;
 245
 246         return nhg->nh_entries[nhsel].nh;
 247 }
 248
 249 static inline
 250 int nexthop_mpath_fill_node(struct sk_buff *skb, struct nexthop *nh,
 251                             u8 rt_family)
 252 {
 253         struct nh_group *nhg = rtnl_dereference(nh->nh_grp);
 254         int i;
 255
 256         for (i = 0; i < nhg->num_nh; i++) {
 257                 struct nexthop *nhe = nhg->nh_entries[i].nh;
 258                 struct nh_info *nhi = rcu_dereference_rtnl(nhe->nh_info);
 259                 struct fib_nh_common *nhc = &nhi->fib_nhc;
 260                 int weight = nhg->nh_entries[i].weight;
 261
 262                 if (fib_add_nexthop(skb, nhc, weight, rt_family) < 0)
 263                         return -EMSGSIZE;
 264         }
 265
 266         return 0;
 267 }
 268
 269 /* called with rcu lock */
 270 static inline bool nexthop_is_blackhole(const struct nexthop *nh)
 271 {
 272         const struct nh_info *nhi;
 273
 274         if (nh->is_group) {
 275                 struct nh_group *nh_grp;
 276
 277                 nh_grp = rcu_dereference_rtnl(nh->nh_grp);
 278                 if (nh_grp->num_nh > 1)
 279                         return false;
 280
 281                 nh = nh_grp->nh_entries[0].nh;
 282         }
 283
 284         nhi = rcu_dereference_rtnl(nh->nh_info);
 285         return nhi->reject_nh;
 286 }
 287
 288 static inline void nexthop_path_fib_result(struct fib_result *res, int hash)
 289 {
 290         struct nh_info *nhi;
 291         struct nexthop *nh;
 292
 293         nh = nexthop_select_path(res->fi->nh, hash);
 294         nhi = rcu_dereference(nh->nh_info);
 295         res->nhc = &nhi->fib_nhc;
 296 }
 297
 298 /* called with rcu read lock or rtnl held */
 299 static inline
 300 struct fib_nh_common *nexthop_fib_nhc(struct nexthop *nh, int nhsel)
 301 {
 302         struct nh_info *nhi;
 303
 304         BUILD_BUG_ON(offsetof(struct fib_nh, nh_common) != 0);
 305         BUILD_BUG_ON(offsetof(struct fib6_nh, nh_common) != 0);
 306
 307         if (nh->is_group) {
 308                 struct nh_group *nh_grp;
 309
 310                 nh_grp = rcu_dereference_rtnl(nh->nh_grp);
 311                 if (nh_grp->mpath) {
 312                         nh = nexthop_mpath_select(nh_grp, nhsel);
 313                         if (!nh)
 314                                 return NULL;
 315                 }
 316         }
 317
 318         nhi = rcu_dereference_rtnl(nh->nh_info);
 319         return &nhi->fib_nhc;
 320 }
 321
 322 /* called from fib_table_lookup with rcu_lock */
 323 static inline
 324 struct fib_nh_common *nexthop_get_nhc_lookup(const struct nexthop *nh,
 325                                              int fib_flags,
 326                                              const struct flowi4 *flp,
 327                                              int *nhsel)
 328 {
 329         struct nh_info *nhi;
 330
 331         if (nh->is_group) {
 332                 struct nh_group *nhg = rcu_dereference(nh->nh_grp);
 333                 int i;
 334
 335                 for (i = 0; i < nhg->num_nh; i++) {
 336                         struct nexthop *nhe = nhg->nh_entries[i].nh;
 337
 338                         nhi = rcu_dereference(nhe->nh_info);
 339                         if (fib_lookup_good_nhc(&nhi->fib_nhc, fib_flags, flp)) {
 340                                 *nhsel = i;
 341                                 return &nhi->fib_nhc;
 342                         }
 343                 }
 344         } else {
 345                 nhi = rcu_dereference(nh->nh_info);
 346                 if (fib_lookup_good_nhc(&nhi->fib_nhc, fib_flags, flp)) {
 347                         *nhsel = 0;
 348                         return &nhi->fib_nhc;
 349                 }
 350         }
 351
 352         return NULL;
 353 }
 354
 355 static inline bool nexthop_uses_dev(const struct nexthop *nh,
 356                                     const struct net_device *dev)
 357 {
 358         struct nh_info *nhi;
 359
 360         if (nh->is_group) {
 361                 struct nh_group *nhg = rcu_dereference(nh->nh_grp);
 362                 int i;
 363
 364                 for (i = 0; i < nhg->num_nh; i++) {
 365                         struct nexthop *nhe = nhg->nh_entries[i].nh;
 366
 367                         nhi = rcu_dereference(nhe->nh_info);
 368                         if (nhc_l3mdev_matches_dev(&nhi->fib_nhc, dev))
 369                                 return true;
 370                 }
 371         } else {
 372                 nhi = rcu_dereference(nh->nh_info);
 373                 if (nhc_l3mdev_matches_dev(&nhi->fib_nhc, dev))
 374                         return true;
 375         }
 376
 377         return false;
 378 }
 379
 380 static inline unsigned int fib_info_num_path(const struct fib_info *fi)
 381 {
 382         if (unlikely(fi->nh))
 383                 return nexthop_num_path(fi->nh);
 384
 385         return fi->fib_nhs;
 386 }
 387
 388 int fib_check_nexthop(struct nexthop *nh, u8 scope,
 389                       struct netlink_ext_ack *extack);
 390
 391 static inline struct fib_nh_common *fib_info_nhc(struct fib_info *fi, int nhsel)
 392 {
 393         if (unlikely(fi->nh))
 394                 return nexthop_fib_nhc(fi->nh, nhsel);
 395
 396         return &fi->fib_nh[nhsel].nh_common;
 397 }
 398
 399 /* only used when fib_nh is built into fib_info */
 400 static inline struct fib_nh *fib_info_nh(struct fib_info *fi, int nhsel)
 401 {
 402         WARN_ON(fi->nh);
 403
 404         return &fi->fib_nh[nhsel];
 405 }
 406
 407 /*
 408  * IPv6 variants
 409  */
 410 int fib6_check_nexthop(struct nexthop *nh, struct fib6_config *cfg,
 411                        struct netlink_ext_ack *extack);
 412
 413 static inline struct fib6_nh *nexthop_fib6_nh(struct nexthop *nh)
 414 {
 415         struct nh_info *nhi;
 416
 417         if (nh->is_group) {
 418                 struct nh_group *nh_grp;
 419
 420                 nh_grp = rcu_dereference_rtnl(nh->nh_grp);
 421                 nh = nexthop_mpath_select(nh_grp, 0);
 422                 if (!nh)
 423                         return NULL;
 424         }
 425
 426         nhi = rcu_dereference_rtnl(nh->nh_info);
 427         if (nhi->family == AF_INET6)
 428                 return &nhi->fib6_nh;
 429
 430         return NULL;
 431 }
 432
 433 static inline struct net_device *fib6_info_nh_dev(struct fib6_info *f6i)
 434 {
 435         struct fib6_nh *fib6_nh;
 436
 437         fib6_nh = f6i->nh ? nexthop_fib6_nh(f6i->nh) : f6i->fib6_nh;
 438         return fib6_nh->fib_nh_dev;
 439 }
 440
 441 static inline void nexthop_path_fib6_result(struct fib6_result *res, int hash)
 442 {
 443         struct nexthop *nh = res->f6i->nh;
 444         struct nh_info *nhi;
 445
 446         nh = nexthop_select_path(nh, hash);
 447
 448         nhi = rcu_dereference_rtnl(nh->nh_info);
 449         if (nhi->reject_nh) {
 450                 res->fib6_type = RTN_BLACKHOLE;
 451                 res->fib6_flags |= RTF_REJECT;
 452                 res->nh = nexthop_fib6_nh(nh);
 453         } else {
 454                 res->nh = &nhi->fib6_nh;
 455         }
 456 }
 457
 458 int nexthop_for_each_fib6_nh(struct nexthop *nh,
 459                              int (*cb)(struct fib6_nh *nh, void *arg),
 460                              void *arg);
 461
 462 static inline int nexthop_get_family(struct nexthop *nh)
 463 {
 464         struct nh_info *nhi = rcu_dereference_rtnl(nh->nh_info);
 465
 466         return nhi->family;
 467 }
 468
 469 static inline
 470 struct fib_nh_common *nexthop_fdb_nhc(struct nexthop *nh)
 471 {
 472         struct nh_info *nhi = rcu_dereference_rtnl(nh->nh_info);
 473
 474         return &nhi->fib_nhc;
 475 }
 476
 477 static inline struct fib_nh_common *nexthop_path_fdb_result(struct nexthop *nh,
 478                                                             int hash)
 479 {
 480         struct nh_info *nhi;
 481         struct nexthop *nhp;
 482
 483         nhp = nexthop_select_path(nh, hash);
 484         if (unlikely(!nhp))
 485                 return NULL;
 486         nhi = rcu_dereference(nhp->nh_info);
 487         return &nhi->fib_nhc;
 488 }
 489 #endif